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1.
Neuron ; 112(11): 1876-1890.e4, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38447579

RESUMO

In complex environments, animals can adopt diverse strategies to find rewards. How distinct strategies differentially engage brain circuits is not well understood. Here, we investigate this question, focusing on the cortical Vip-Sst disinhibitory circuit between vasoactive intestinal peptide-postive (Vip) interneurons and somatostatin-positive (Sst) interneurons. We characterize the behavioral strategies used by mice during a visual change detection task. Using a dynamic logistic regression model, we find that individual mice use mixtures of a visual comparison strategy and a statistical timing strategy. Separately, mice also have periods of task engagement and disengagement. Two-photon calcium imaging shows large strategy-dependent differences in neural activity in excitatory, Sst inhibitory, and Vip inhibitory cells in response to both image changes and image omissions. In contrast, task engagement has limited effects on neural population activity. We find that the diversity of neural correlates of strategy can be understood parsimoniously as the increased activation of the Vip-Sst disinhibitory circuit during the visual comparison strategy, which facilitates task-appropriate responses.


Assuntos
Interneurônios , Somatostatina , Peptídeo Intestinal Vasoativo , Córtex Visual , Animais , Peptídeo Intestinal Vasoativo/metabolismo , Córtex Visual/fisiologia , Camundongos , Somatostatina/metabolismo , Interneurônios/fisiologia , Inibição Neural/fisiologia , Masculino , Camundongos Endogâmicos C57BL , Estimulação Luminosa/métodos , Percepção Visual/fisiologia
2.
Chaos ; 33(8)2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37561121

RESUMO

Inhibitory interneurons in the cortex are abundant and have diverse roles, classified as parvalbumin (PV), somatostatin (SOM), and vasoactive intestinal polypeptide (VIP) according to chemically defined categories. Currently, their involvement with seizures has been partially uncovered in physiological terms. Here, we propose a corticothalamic model containing heterogeneous interneurons to study the effects of various interneurons on absence seizure dynamics by means of optogenetic stimulation. First, the important role of feedforward inhibition caused by SRN→PV→PN projections on seizures is verified. Then, we demonstrate that light activation targeting either PV or SOM INs can control seizures. Finally, with different inhibition contributions from PV INs and SOM INs, the possible disinhibitory effect of blue light acting on VIP INs is mainly discussed. The results suggest that depending on the inhibition degree of both types, the disinhibition brought about by the VIP INs will trigger seizures, will control seizures, and will not work or cause the PNs to tend toward a high saturation state with high excitability. The circuit mechanism and the related bifurcation characteristics in various cases are emphatically revealed. In the model presented, in addition to Hopf and saddle-node bifurcations, the system may also undergo period-doubling and torus bifurcations under stimulus action, with more complex dynamics. Our work may provide a theoretical basis for understanding and further exploring the role of heterogeneous interneurons, in particular, the VIP INs, a novel target, in absence seizures.


Assuntos
Interneurônios , Convulsões , Humanos , Interneurônios/fisiologia , Córtex Cerebral/metabolismo , Inibição Neural/fisiologia , Peptídeo Intestinal Vasoativo/metabolismo , Parvalbuminas
3.
Nature ; 620(7973): 366-373, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37468637

RESUMO

Neurons in the posterior parietal cortex contribute to the execution of goal-directed navigation1 and other decision-making tasks2-4. Although molecular studies have catalogued more than 50 cortical cell types5, it remains unclear what distinct functions they have in this area. Here we identified a molecularly defined subset of somatostatin (Sst) inhibitory neurons that, in the mouse posterior parietal cortex, carry a cell-type-specific error-correction signal for navigation. We obtained repeatable experimental access to these cells using an adeno-associated virus in which gene expression is driven by an enhancer that functions specifically in a subset of Sst cells6. We found that during goal-directed navigation in a virtual environment, this subset of Sst neurons activates in a synchronous pattern that is distinct from the activity of surrounding neurons, including other Sst neurons. Using in vivo two-photon photostimulation and ex vivo paired patch-clamp recordings, we show that nearby cells of this Sst subtype excite each other through gap junctions, revealing a self-excitation circuit motif that contributes to the synchronous activity of this cell type. These cells selectively activate as mice execute course corrections for deviations in their virtual heading during navigation towards a reward location, for both self-induced and experimentally induced deviations. We propose that this subtype of Sst neurons provides a self-reinforcing and cell-type-specific error-correction signal in the posterior parietal cortex that may help with the execution and learning of accurate goal-directed navigation trajectories.


Assuntos
Neurônios , Lobo Parietal , Animais , Camundongos , Aprendizagem , Neurônios/metabolismo , Lobo Parietal/citologia , Lobo Parietal/metabolismo , Objetivos , Somatostatina/metabolismo , Inibição Neural , Navegação Espacial , Técnicas de Patch-Clamp , Junções Comunicantes/metabolismo
4.
Brain Res ; 1812: 148380, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-37121425

RESUMO

RATIONALE: Modulation of cortical excitability, in particular inhibition, is impaired in patients with schizophrenia. Chronic nicotine consumption, which is prevalent in this group, has been shown to alter cortical excitability in healthy individuals and to increase inhibitory activity. Thus, beneficial effects of smoking on impaired cortical excitability in patients with schizophrenia have been proposed, though direct experimental evidence is still lacking. OBJECTIVES: We aimed to explore the effect of chronic smoking on cortical excitability by comparing smoking and non-smoking patients with schizophrenia. METHOD: Twenty-six smoking and 19 non-smoking patients diagnosed with schizophrenia were included. Transcranial magnetic stimulation (TMS) applied to the primary motor cortex served as experimental paradigm for measuring corticospinal and intracortical excitability as follows: Resting motor threshold (RMT) and the input/output curve (I/O curve) were obtained to assess corticospinal excitability. Intracortical excitability was explored using paired-pulse TMS techniques (intracortical facilitation (ICF), short-latency intracortical inhibition (SICI) and short-latency afferent inhibition (SAI)). RESULTS: A significantly stronger inhibition in the cholinergically driven SAI protocol was observed in smokers compared to non-smokers. All other measures did not show significant differences between groups. CONCLUSION: Our results suggest an increased inhibition within cholinergic circuits due to chronic nicotine consumption in schizophrenia. This increase may compensate impaired cholinergic neurotransmission and could explain the high rate of smokers in schizophrenia.


Assuntos
Córtex Motor , Esquizofrenia , Humanos , Nicotina/farmacologia , Fumar , Potencial Evocado Motor/fisiologia , Córtex Motor/fisiologia , Estimulação Magnética Transcraniana/métodos , Colinérgicos/farmacologia , Inibição Neural/fisiologia
5.
Pediatr Neurol ; 143: 34-43, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36996759

RESUMO

BACKGROUND: Neurofibromatosis type 1 (NF1) is a genetic neurocutaneous disorder commonly associated with motor and cognitive symptoms that greatly impact quality of life. Transcranial magnetic stimulation (TMS) can quantify motor cortex physiology, reflecting the basis for impaired motor function as well as, possibly, clues for mechanisms of effective treatment. We hypothesized that children with NF1 have impaired motor function and altered motor cortex physiology compared to typically developing (TD) control children and children with attention-deficit/hyperactivity disorder (ADHD). METHODS: Children aged 8-17 years with NF1 (n = 21) were compared to children aged 8-12 years with ADHD (n = 59) and TD controls (n = 88). Motor development was assessed using the Physical and Neurological Examination for Subtle Signs (PANESS) scale. The balance of inhibition and excitation in motor cortex was assessed using the TMS measures short-interval cortical inhibition (SICI) and intracortical facilitation (ICF). Measures were compared by diagnosis and tested using bivariate correlations and regression for association with clinical characteristics. RESULTS: In NF1, ADHD severity scores were intermediate between the ADHD and TD cohorts, but total PANESS scores were markedly elevated (worse) compared to both (P < 0.001). Motor cortex ICF (excitatory) was significantly lower in NF1 than in TD and ADHD (P < 0.001), but SICI (inhibitory) did not differ. However, in NF1, better PANESS scores correlated with lower SICI ratios (more inhibition; ρ = 0.62, P = 0.003) and lower ICF ratios (less excitation; ρ = 0.38, P = 0.06). CONCLUSIONS: TMS-evoked SICI and ICF may reflect processes underlying abnormal motor function in children with NF1.


Assuntos
Inibição Neural , Neurofibromatose 1 , Criança , Humanos , Adolescente , Inibição Neural/fisiologia , Neurofibromatose 1/complicações , Qualidade de Vida , Potencial Evocado Motor/fisiologia , Eletromiografia , Estimulação Magnética Transcraniana
6.
Neurobiol Dis ; 174: 105881, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36202290

RESUMO

Fragile-X syndrome (FXS) and Neurofibromatosis of type 1 (NF-1) are two monogenic disorders sharing neurobehavioral symptoms and pathophysiological mechanisms. Namely, preclinical models of both conditions show overactivity of the mTOR signaling pathway as well as GABAergic alterations. However, despite its potential clinical relevance for these disorders, the GABAergic system has not been systematically studied in humans. In the present study, we used an extensive transcranial magnetic stimulation (TMS) assessment battery in combination with magnetic resonance spectroscopy (MRS) to provide a comprehensive picture of the main inhibitory neurotransmitter system in patients with FXS and NF1. Forty-three participants took part in the TMS session (15 FXS, 10 NF1, 18 controls) and 36 in the MRS session (11 FXS, 14 NF1, 11 controls). Results show that, in comparison to healthy control participants, individuals with FXS and NF1 display lower GABA concentration levels as measured with MRS. TMS result show that FXS patients present increased GABAB-mediated inhibition compared to controls and NF1 patients, and that GABAA-mediated intracortical inhibition was associated with increased excitability specifically in the FXS groups. In line with previous reports, correlational analyses between MRS and TMS measures did not show significant relationships between GABA-related metrics, but several TMS measures correlated with glutamate+glutamine (Glx) levels assessed with MRS. Overall, these results suggest a partial overlap in neurophysiological alterations involving the GABA system in NF1 and FXS, and support the hypothesis that MRS and TMS assess different aspects of the neurotransmitter systems.


Assuntos
Síndrome do Cromossomo X Frágil , Córtex Motor , Neurofibromatose 1 , Humanos , Inibição Neural/fisiologia , Ácido gama-Aminobutírico/metabolismo , Estimulação Magnética Transcraniana , Neurofibromatose 1/metabolismo
7.
Sci Rep ; 12(1): 13814, 2022 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-35970940

RESUMO

Neurofibromatosis type 1 (NF1) is associated with GABAergic dysfunction which has been suggested as the underlying cause of cognitive impairments. Previous intervention trials investigated the statins' effects using cognitive outcome measures. However, available outcome measures have led to inconclusive results and there is a need to identify other options. Here, we aimed at investigating alternative outcome measures in a feasibility trial targeting cortical inhibition mechanisms known to be altered in NF1. We explored the neurochemical and physiological changes elicited by lovastatin, with magnetic resonance spectroscopy and transcranial magnetic stimulation (TMS). Fifteen NF1 adults participated in this randomized, triple-blind, placebo-controlled crossover trial (Clinicaltrials.gov NCT03826940) composed of one baseline and two reassessment visits after lovastatin/placebo intake (60 mg/day, 3-days). Motor cortex GABA+ and Glx concentrations were measured using HERMES and PRESS sequences, respectively. Cortical inhibition was investigated by paired-pulse, input-output curve, and cortical silent period (CSP) TMS protocols. CSP ratios were significantly increased by lovastatin (relative: p = 0.027; absolute: p = 0.034) but not by placebo. CSP durations showed a negative correlation with the LICI 50 ms amplitude ratio. Lovastatin was able to modulate cortical inhibition in NF1, as assessed by TMS CSP ratios. The link between this modulation of cortical inhibition and clinical improvements should be addressed by future large-scale studies.


Assuntos
Potencial Evocado Motor , Neurofibromatose 1 , Adulto , Potencial Evocado Motor/fisiologia , Humanos , Lovastatina/farmacologia , Lovastatina/uso terapêutico , Inibição Neural/fisiologia , Neurofibromatose 1/tratamento farmacológico , Estimulação Magnética Transcraniana/métodos
8.
J Neurosci ; 42(14): 2942-2950, 2022 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-35181596

RESUMO

Inhibitory microcircuits play an essential role in regulating cortical responses to sensory stimuli. Interneurons that inhibit dendritic or somatic integration act as gatekeepers for neural activity, synaptic plasticity, and the formation of sensory representations. Conversely, interneurons that selectively inhibit other interneurons can open gates through disinhibition. In the anterior piriform cortex, relief of inhibition permits associative LTP of excitatory synapses between pyramidal neurons. However, the interneurons and circuits mediating disinhibition have not been elucidated. In this study, we use an optogenetic approach in mice of both sexes to identify the inhibitory interneurons and disinhibitory circuits that regulate LTP. We focused on three prominent interneuron classes: somatostatin (SST), parvalbumin (PV), and vasoactive intestinal polypeptide (VIP) interneurons. We find that LTP is gated by the inactivation SST or PV interneurons and by the activation of VIP interneurons. Further, VIP interneurons strongly inhibit putative SST cells during LTP induction but only weakly inhibit PV interneurons. Together, these findings suggest that VIP interneurons mediate a disinhibitory circuit that gates synaptic plasticity during the formation of olfactory representations.SIGNIFICANCE STATEMENT Inhibitory interneurons stabilize neural activity during sensory processing. However, inhibition must also be modulated to allow sensory experience shape neural responses. In olfactory cortex, inhibition regulates activity-dependent increases in excitatory synaptic strength that accompany odor learning. We identify two inhibitory interneuron classes that act as gatekeepers preventing excitatory enhancement. We demonstrate that driving a third class of interneurons inhibits the gatekeepers and opens the gate for excitatory enhancement. All three inhibitory neuron classes comprise disinhibitory microcircuit motifs found throughout the cortex. Our findings suggest that a common disinhibitory microcircuit promotes changes in synaptic strength during sensory processing and learning.


Assuntos
Interneurônios , Córtex Piriforme , Animais , Feminino , Interneurônios/fisiologia , Masculino , Camundongos , Inibição Neural/fisiologia , Plasticidade Neuronal/fisiologia , Parvalbuminas/metabolismo , Córtex Piriforme/metabolismo , Células Piramidais/fisiologia , Peptídeo Intestinal Vasoativo/metabolismo
9.
Cell Rep ; 38(7): 110383, 2022 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-35172159

RESUMO

In the olfactory bulb (OB), olfactory information represented by mitral/tufted cells (M/Ts) is extensively modulated by local inhibitory interneurons before being transmitted to the olfactory cortex. While the crucial roles of cortical vasoactive-intestinal-peptide-expressing (VIP) interneurons have been extensively studied, their precise function in the OB remains elusive. Here, we identify the synaptic connectivity of VIP interneurons onto mitral cells (MCs) and demonstrate their important role in olfactory behaviors. Optogenetic activation of VIP interneurons reduced both spontaneous and odor-evoked activity of M/Ts in awake mice. Whole-cell recordings revealed that VIP interneurons decrease MC firing through direct inhibitory synaptic connections with MCs. Furthermore, inactivation of VIP interneurons leads to increased MC firing and impaired olfactory detection and odor discrimination. Therefore, our results demonstrate that VIP interneurons control OB output and play critical roles in odor processing and olfactory behaviors.


Assuntos
Discriminação Psicológica , Interneurônios/fisiologia , Odorantes , Bulbo Olfatório/fisiologia , Peptídeo Intestinal Vasoativo/metabolismo , Animais , Ritmo beta/fisiologia , Feminino , Ritmo Gama/fisiologia , Masculino , Camundongos , Inibição Neural/fisiologia , Sinapses/fisiologia , Vigília/fisiologia
10.
Science ; 375(6576): eabl5981, 2022 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-34990233

RESUMO

Although single-cell transcriptomics of the neocortex has uncovered more than 300 putative cell types, whether this molecular classification predicts distinct functional roles is unclear. We combined two-photon calcium imaging with spatial transcriptomics to functionally and molecularly investigate cortical circuits. We characterized behavior-related responses across major neuronal subclasses in layers 2 or 3 of the primary somatosensory cortex as mice performed a tactile working memory task. We identified an excitatory intratelencephalic cell type, Baz1a, that exhibits high tactile feature selectivity. Baz1a neurons homeostatically maintain stimulus responsiveness during altered experience and show persistent enrichment of subsets of immediately early genes. Functional and anatomical connectivity reveals that Baz1a neurons residing in upper portions of layers 2 or 3 preferentially innervate somatostatin-expressing inhibitory neurons. This motif defines a circuit hub that orchestrates local sensory processing in superficial layers of the neocortex.


Assuntos
Rede Nervosa/fisiologia , Neurônios/fisiologia , Córtex Somatossensorial/citologia , Córtex Somatossensorial/fisiologia , Animais , Comportamento Animal , Cálcio/análise , Expressão Gênica , Genes fos , Memória de Curto Prazo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Inibição Neural , Tato , Transcriptoma , Vibrissas/fisiologia
11.
Pain ; 163(5): e675-e688, 2022 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-34490851

RESUMO

ABSTRACT: Networks of the dorsal horn of the spinal cord process nociceptive information from the periphery. In these networks, the excitation-inhibition balance is critical to shape this nociceptive information and to gate it to the brain where it is interpreted as pain. Our aim was to define whether short-term plasticity of inhibitory connections could tune this inhibition-excitation balance by differentially controlling excitatory and inhibitory microcircuits. To this end, we used spinal cord slices from adult mice expressing enhanced green fluorescent protein (eGFP) under the GAD65 promoter and recorded from both eGFP+ (putative inhibitory) and eGFP- (putative excitatory) neurons of lamina II while stimulating single presynaptic GABAergic interneurons at various frequencies. Our results indicate that GABAergic neurons of lamina II simultaneously contact eGFP- and eGFP+ neurons, but these connections display very different frequency-dependent short-term plasticities. Connections onto eGFP- interneurons displayed limited frequency-dependent changes and strong time-dependent summation of inhibitory synaptic currents that was however subjected to a tonic activity-dependent inhibition involving A1 adenosine receptors. By contrast, GABAergic connections onto eGFP+ interneurons expressed pronounced frequency-dependent depression, thus favoring disinhibition at these synapses by a mechanism involving the activation of GABAB autoreceptors at low frequency. Interestingly, the balance favors inhibition at frequencies associated with intense pain, whereas it favors excitation at frequencies associated with low pain. Therefore, these target-specific and frequency-specific plasticities allow to tune the balance between inhibition and disinhibition while processing frequency-coded information from primary afferents. These short-term plasticities and their modulation by A1 and GABAB receptors might represent an interesting target in pain-alleviating strategies.


Assuntos
Nociceptividade , Células do Corno Posterior , Animais , Neurônios GABAérgicos , Interneurônios/fisiologia , Camundongos , Inibição Neural/fisiologia , Dor/metabolismo , Células do Corno Posterior/metabolismo , Corno Dorsal da Medula Espinal
12.
Biochim Biophys Acta Mol Cell Res ; 1869(1): 119146, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34599984

RESUMO

Gaba-ergic neurons are a diverse cell class with extensive influence over cortical processing, but their role in experience-dependent plasticity is not completely understood. Here we addressed the role of cortical somatostatin- (SOM-INs) and vasoactive intestinal polypeptide- (VIP-INs) containing interneurons in a Pavlovian conditioning where stimulation of the vibrissae is used as a conditioned stimulus and tail shock as unconditioned one. This procedure induces a plastic change observed as an enlargement of the cortical functional representation of vibrissae activated during conditioning. Using layer-targeted, cell-selective DREADD transductions, we examined the involvement of SOM-INs and VIP-INs activity in learning-related plastic changes. Under optical recordings, we injected DREADD-expressing vectors into layer IV (L4) barrels or layer II/III (L2/3) areas corresponding to the activated vibrissae. The activity of the interneurons was modulated during all conditioning sessions, and functional 2-deoxyglucose (2DG) maps were obtained 24 h after the last session. In mice with L4 but not L2/3 SOM-INs suppressed during conditioning, the plastic change of whisker representation was absent. The behavioral effect of conditioning was disturbed. Both L4 SOM-INs excitation and L2/3 VIP-INs inhibition during conditioning did not affect the plasticity or the conditioned response. We found the activity of L4 SOM-INs is indispensable in the formation of learning-induced plastic change. We propose that L4 SOM-INs may provide disinhibition by blocking L4 parvalbumin interneurons, allowing a flow of information into upper cortical layers during learning.


Assuntos
Interneurônios/fisiologia , Aprendizagem , Inibição Neural , Plasticidade Neuronal , Córtex Somatossensorial/fisiologia , Animais , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/fisiologia , Interneurônios/efeitos dos fármacos , Interneurônios/metabolismo , Moduladores de Transporte de Membrana/farmacologia , Camundongos , Córtex Somatossensorial/citologia , Somatostatina/genética , Somatostatina/metabolismo , Vibrissas/inervação , Vibrissas/fisiologia
13.
Neural Plast ; 2021: 5607898, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34721569

RESUMO

Spinal cord stimulation (SCS) as an evidence-based interventional treatment has been used and approved for clinical use in a variety of pathological states including peripheral neuropathic pain; however, until now, it has not been used for the treatment of spinal cord injury- (SCI-) induced central neuropathic pain. This paper reviews the underlying mechanisms of SCS-induced analgesia and its clinical application in the management of peripheral and central neuropathic pain. Evidence from recent research publications indicates that nociceptive processing at peripheral and central sensory systems is thought to be modulated by SCS through (i) inhibition of the ascending nociceptive transmission by the release of analgesic neurotransmitters such as GABA and endocannabinoids at the spinal dorsal horn; (ii) facilitation of the descending inhibition by release of noradrenalin, dopamine, and serotonin acting on their receptors in the spinal cord; and (iii) activation of a variety of supraspinal brain areas related to pain perception and emotion. These insights into the mechanisms have resulted in the clinically approved use of SCS in peripheral neuropathic pain states like Complex Regional Pain Syndrome (CRPS) and Failed Back Surgery Syndrome (FBSS). However, the mechanisms underlying SCS-induced pain relief in central neuropathic pain are only partly understood, and more research is needed before this therapy can be implemented in SCI patients with central neuropathic pain.


Assuntos
Inibição Neural/fisiologia , Neuralgia/fisiopatologia , Neuralgia/terapia , Manejo da Dor/métodos , Estimulação da Medula Espinal/métodos , Humanos , Medula Espinal/fisiopatologia , Estimulação da Medula Espinal/tendências , Resultado do Tratamento
14.
Nat Commun ; 12(1): 6112, 2021 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-34671051

RESUMO

Stroke profoundly disrupts cortical excitability which impedes recovery, but how it affects the function of specific inhibitory interneurons, or subpopulations therein, is poorly understood. Interneurons expressing vasoactive intestinal peptide (VIP) represent an intriguing stroke target because they can regulate cortical excitability through disinhibition. Here we chemogenetically augmented VIP interneuron excitability in a murine model of photothrombotic stroke and show that it enhances somatosensory responses and improves recovery of paw function. Using longitudinal calcium imaging, we discovered that stroke primarily disrupts the fidelity (fraction of responsive trials) and predictability of sensory responses within a subset of highly active VIP neurons. Partial recovery of responses occurred largely within these active neurons and was not accompanied by the recruitment of minimally active neurons. Importantly, chemogenetic stimulation preserved sensory response fidelity and predictability in highly active neurons. These findings provide a new depth of understanding into how stroke and prospective therapies (chemogenetics), can influence subpopulations of inhibitory interneurons.


Assuntos
Interneurônios/fisiologia , Acidente Vascular Cerebral/terapia , Peptídeo Intestinal Vasoativo/metabolismo , Animais , Clozapina/análogos & derivados , Clozapina/uso terapêutico , Humanos , Interneurônios/efeitos dos fármacos , Interneurônios/metabolismo , Camundongos , Inibição Neural/efeitos dos fármacos , Receptor Muscarínico M3/genética , Receptor Muscarínico M3/metabolismo , Recuperação de Função Fisiológica , Córtex Somatossensorial/citologia , Córtex Somatossensorial/efeitos dos fármacos , Córtex Somatossensorial/fisiologia , Acidente Vascular Cerebral/metabolismo , Acidente Vascular Cerebral/fisiopatologia
15.
Cell Rep ; 37(3): 109837, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34686328

RESUMO

The selection of goal-directed behaviors is supported by neural circuits located within the frontal cortex. Frontal cortical afferents arise from multiple brain areas, yet the cell-type-specific targeting of these inputs is unclear. Here, we use monosynaptic retrograde rabies mapping to examine the distribution of afferent neurons targeting distinct classes of local inhibitory interneurons and excitatory projection neurons in mouse infralimbic frontal cortex. Interneurons expressing parvalbumin, somatostatin, or vasoactive intestinal peptide receive a large proportion of inputs from the hippocampus, while interneurons expressing neuron-derived neurotrophic factor receive a large proportion of inputs from thalamic regions. A similar dichotomy is present among the four different excitatory projection neurons. These results show a prominent bias among long-range hippocampal and thalamic afferent systems in their targeting to specific sets of frontal cortical neurons. Moreover, they suggest the presence of two distinct local microcircuits that control how different inputs govern frontal cortical information processing.


Assuntos
Lobo Frontal/fisiologia , Hipocampo/fisiologia , Interneurônios/fisiologia , Sinapses/fisiologia , Tálamo/fisiologia , Animais , Comportamento Animal , Lobo Frontal/citologia , Lobo Frontal/metabolismo , Hipocampo/citologia , Hipocampo/metabolismo , Interneurônios/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fatores de Crescimento Neural/genética , Fatores de Crescimento Neural/metabolismo , Inibição Neural , Vias Neurais/citologia , Vias Neurais/metabolismo , Vias Neurais/fisiologia , Técnicas de Rastreamento Neuroanatômico , Parvalbuminas/genética , Parvalbuminas/metabolismo , Somatostatina/genética , Somatostatina/metabolismo , Sinapses/metabolismo , Tálamo/citologia , Tálamo/metabolismo , Peptídeo Intestinal Vasoativo/genética , Peptídeo Intestinal Vasoativo/metabolismo
17.
Cell Rep ; 36(7): 109563, 2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34407401

RESUMO

Overconsumption of highly palatable, energy-dense food is considered a key driver of the obesity pandemic. The orbitofrontal cortex (OFC) is critical for reward valuation of gustatory signals, yet how the OFC adapts to obesogenic diets is poorly understood. Here, we show that extended access to a cafeteria diet impairs astrocyte glutamate clearance, which leads to a heterosynaptic depression of GABA transmission onto pyramidal neurons of the OFC. This decrease in GABA tone is due to an increase in extrasynaptic glutamate, which acts via metabotropic glutamate receptors to liberate endocannabinoids. This impairs the induction of endocannabinoid-mediated long-term plasticity. The nutritional supplement, N-acetylcysteine rescues this cascade of synaptic impairments by restoring astrocytic glutamate transport. Together, our findings indicate that obesity targets astrocytes to disrupt the delicate balance between excitatory and inhibitory transmission in the OFC.


Assuntos
Astrócitos/patologia , Plasticidade Neuronal , Obesidade/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Acetilcisteína/farmacologia , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Transporte Biológico/efeitos dos fármacos , Dieta , Endocanabinoides/metabolismo , Neurônios GABAérgicos/metabolismo , Ácido Glutâmico/metabolismo , Homeostase/efeitos dos fármacos , Hipertrofia , Masculino , Inibição Neural/efeitos dos fármacos , Inibição Neural/fisiologia , Plasticidade Neuronal/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Ratos Long-Evans , Sinapses/efeitos dos fármacos , Sinapses/metabolismo , Transmissão Sináptica/fisiologia
18.
J Neurosci ; 41(40): 8279-8296, 2021 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-34413209

RESUMO

Experience-dependent formation and removal of inhibitory synapses are essential throughout life. For instance, GABAergic synapses are removed to facilitate learning, and strong excitatory activity is accompanied by the formation of inhibitory synapses to maintain coordination between excitation and inhibition. We recently discovered that active dendrites trigger the growth of inhibitory synapses via CB1 receptor-mediated endocannabinoid signaling, but the underlying mechanism remained unclear. Using two-photon microscopy to monitor the formation of individual inhibitory boutons in hippocampal organotypic slices from mice (both sexes), we found that CB1 receptor activation mediated the formation of inhibitory boutons and promoted their subsequent stabilization. Inhibitory bouton formation did not require neuronal activity and was independent of Gi/o-protein signaling, but was directly induced by elevating cAMP levels using forskolin and by activating Gs-proteins using DREADDs. Blocking PKA activity prevented CB1 receptor-mediated inhibitory bouton formation. Our findings reveal that axonal CB1 receptors signal via unconventional downstream pathways and that inhibitory bouton formation is triggered by an increase in axonal cAMP levels. Our results demonstrate an unexpected role for axonal CB1 receptors in axon-specific, and context-dependent, inhibitory synapse formation.SIGNIFICANCE STATEMENT Coordination between excitation and inhibition is required for proper brain function throughout life. It was previously shown that new inhibitory synapses can be formed in response to strong excitation to maintain this coordination, and this was mediated by endocannabinoid signaling via CB1 receptors. As activation of CB1 receptors generally results in the suppression of synaptic transmission, it remained unclear how CB1 receptors can mediate the formation of inhibitory synapses. Here we show that CB1 receptors on inhibitory axons signal via unconventional intracellular pathways and that inhibitory bouton formation is triggered by an increase in axonal cAMP levels and requires PKA activity. Our findings point to a central role for axonal cAMP signaling in activity-dependent inhibitory synapse formation.


Assuntos
Axônios/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Inibição Neural/fisiologia , Terminações Pré-Sinápticas/metabolismo , Receptor CB1 de Canabinoide/metabolismo , Animais , Axônios/química , AMP Cíclico/genética , Proteínas Quinases Dependentes de AMP Cíclico/genética , Feminino , Hipocampo/química , Hipocampo/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Técnicas de Cultura de Órgãos , Terminações Pré-Sinápticas/química , Receptor CB1 de Canabinoide/genética , Imagem com Lapso de Tempo/métodos
19.
J Neurosci ; 41(39): 8111-8125, 2021 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-34400520

RESUMO

The size and structure of the dendritic arbor play important roles in determining how synaptic inputs of neurons are converted to action potential output. The regulatory mechanisms governing the development of dendrites, however, are insufficiently understood. The evolutionary conserved Ste20/Hippo kinase pathway has been proposed to play an important role in regulating the formation and maintenance of dendritic architecture. A key element of this pathway, Ste20-like kinase (SLK), regulates cytoskeletal dynamics in non-neuronal cells and is strongly expressed throughout neuronal development. However, its function in neurons is unknown. We show that, during development of mouse cortical neurons, SLK has a surprisingly specific role for proper elaboration of higher, ≥ third-order dendrites both in male and in female mice. Moreover, we demonstrate that SLK is required to maintain excitation-inhibition balance. Specifically, SLK knockdown caused a selective loss of inhibitory synapses and functional inhibition after postnatal day 15, whereas excitatory neurotransmission was unaffected. Finally, we show that this mechanism may be relevant for human disease, as dysmorphic neurons within human cortical malformations revealed significant loss of SLK expression. Overall, the present data identify SLK as a key regulator of both dendritic complexity during development and inhibitory synapse maintenance.SIGNIFICANCE STATEMENT We show that dysmorphic neurons of human epileptogenic brain lesions have decreased levels of the Ste20-like kinase (SLK). Decreasing SLK expression in mouse neurons revealed that SLK has essential functions in forming the neuronal dendritic tree and in maintaining inhibitory connections with neighboring neurons.


Assuntos
Córtex Cerebral/metabolismo , Dendritos/genética , Inibição Neural/genética , Proteínas Serina-Treonina Quinases/genética , Sinapses/genética , Transmissão Sináptica/fisiologia , Adolescente , Adulto , Idoso , Animais , Córtex Cerebral/patologia , Criança , Pré-Escolar , Dendritos/metabolismo , Dendritos/patologia , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Proteínas Serina-Treonina Quinases/metabolismo , Sinapses/metabolismo , Sinapses/patologia , Adulto Jovem
20.
Neurosci Lett ; 761: 136120, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34280504

RESUMO

Exposure to nicotine during adolescence may cause neurophysiological changes and increase the risks of developing nicotine dependence; it can even lead to lifelong smoking. The intake of nicotine may also lead to abnormal patterns of oscillatory brain activity and inhibition control deficits. However, little is known about the specific relationship between oscillatory brain activity during the resting state and inhibition control capacity in young smokers. In the present study, we acquired resting-state electroencephalography (EEG) data from thirty-four young smokers and 39 age-matched non-smoking controls. Inhibition control performance was measured by a Go/NoGo task. Compared with non-smoking controls, we detected reduced low-frequency delta band activity in the frontal, central and posterior cortices of young smokers. Furthermore, young smokers committed more errors in response to infrequent NoGo trials. Notably, we demonstrated that delta absolute power in the frontal region was negatively correlated with NoGo errors and that alpha power in the central region was positively correlated with NoGo errors in non-smoking controls but not in young smokers. These findings may suggest that these inhibitory control processes were associated with alterations in oscillatory brain activity during the resting state. Our findings suggest that alterations of power spectra in delta bands may act as a useful biomarker of inhibitory control performance and provide a scientific basis for the diagnosis and treatment of nicotine addiction in adolescents.


Assuntos
Ondas Encefálicas , Inibição Neural , Fumar Tabaco/fisiopatologia , Humanos , Masculino , Córtex Sensório-Motor/fisiopatologia , Adulto Jovem
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